Current commercially available self-sealing pipette tip filters can block aqueous-based solutions containing up to about 40% by volume organic solvent, such as isopropanol (IPA) or dimethylsulfoxide (DMSO), from passing through the filter when the solution contacts the filter during over pipetting. However, these self-sealing pipette tip filters do not block aqueous-based solutions containing organic solvents of more than 40% from passing through the filter when the solution contacts the filter during over pipetting. Accordingly, what is needed are self-sealing pipette tip filters that not only block pure water and water based solutions containing less than 40% organic solvents, but also block solutions that are organic solvents and aqueous mixtures, wherein the organic solvents are at concentrations greater than about 40%. Also needed are self-sealing pipette tip filters that block non-aqueous based polar organic solutions. Also needed are self-sealing pipette tip filters that block pure polar organic solvents.
In addition to self-sealing pipette tip filters, self-sealing media are also useful as non-mechanical check valves to prevent liquid from passing through upon contact, such as in a suction canister. Current non-mechanical check valves have similar compositions as self-sealing pipette tip filters and do not block solutions that contain more than 40% organic solvent and less than 60% of water. There is market need to have non-mechanical valves that not only block pure water and water based solutions containing less than 40% organic solvents, but also block solutions that are organic solvents and aqueous mixtures, wherein the organic solvents are at concentrations greater than about 40%. Commercially available self-sealing media also do not block acidic aqueous solutions or organic acid solutions at low concentrations. Non-mechanical valves are needed that block non-aqueous based polar organic solutions. Also needed are non-mechanical valves that block pure polar organic solvents. What is also needed are self-sealing media that block aqueous solutions of inorganic acids or organic acids at concentrations of at least about 5%.